Brachioradial pruritus is associated with a reduction in cutaneous innervation that normalizes during the symptom-free remissions

Abstract

There has been a controversy regarding the cause of brachioradial pruritus: is it caused by a nerve compression in the cervical spine or is it caused by a prolonged exposure to sunlight? The purpose was to study clinical features of patients with brachioradial pruritus and to compare the cutaneous innervation in punch biopsies from the itchy skin of patients with the age-matched controls. Skin biopsy specimens from itchy skin of 16 patients with brachioradial pruritus were collected during the early autumn and were compared with corresponding skin specimens from 11 age-matched controls in the early spring, four of the patients being their own controls. The cutaneous innervation was visualized by antibodies against protein gene product 9.5 (general neuronal marker), by antibodies against calcitonin gene-related peptide (marker for thin sensory nerve fibers), and by antibodies against VR1-receptor (marker for capsaicin-sensitive nerve fibers). In all but two of the patients, itching of the arms or shoulders was seasonal. Some patients reported neck pain. In the skin of the lower arm, the number of protein gene product 9.5 immunoreactive nerve fibers was reduced 23% as compared with controls ( P = .03), the number of intraepithelial nerve fibers being reduced by 27% ( P = .03). The number of calcitonin gene-related peptide immunoreactive nerve fibers in the dermis was reduced by 34% ( P = .02) and the number of capsaicin-sensitive nerve fibers by 43% ( P = .008). The innervation of the four patients who were their own controls became normalized during the symptom-free period. The temporal course of the brachioradial pruritus and the histological changes in the skin similar to those caused by ultraviolet light, indicate that sunlight is an eliciting factor and that cervical spine disease can be a predisposing factor.